Shûhei Sakata framed for his family's murder and left for dead, an ex-hitman will stop at nothing to exact revenge on the masked "demons" who have taken over his city., Supposedly failing to "kill himself" with a gunshot to the head. Though he innocent, he is sent to a prison hospital, where he stays for 15 years, remaining disabled. After he is released, he has a fateful encounter that allows him to recover his physical abilities.